Cadillac & LaSalle Club Discussion Forum

Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: gofast123 on October 28, 2012, 06:27:57 PM

Title: 1985 Eldorado - HT4100 Engine Problems?
Post by: gofast123 on October 28, 2012, 06:27:57 PM
I've heard the stories about this engine many times (iron heads / aluminum block).  I'm looking at an '85 with 25,000 miles on it.  Did GM (Cadillac) have this problem corrected by the 1985 model year?  If not, is there any way to tell if I'm walking into a problem?  Is this a car to stay away from?

Opinions Welcome!  Thanks in advance...
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: austingta on October 28, 2012, 07:08:12 PM
IMHO, the ONLY years to buy that body style are 1979 and 1980. And then, not the diesel. The HT4100 is better than the V8-6-4, but only barely.

I would like to hear other opinions.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: 936CD69 on October 28, 2012, 07:31:09 PM
IMHO the V8-6-4 was INFINITELY better than the early HT like up to 87. In the early 90,s I had to rebuild a 29K HT in an 85 Eldo..two weeks after I bought it. And I would do it again...rather underpowered but the Eldo was a sweet driver
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Dave Shepherd on October 28, 2012, 07:58:40 PM
As mentioned 85 was probably the worst version of the HT, I was a field troubleshooter for Cadillac back then, yikes, we couldn't keep them running, camshafts and subsequent internal engine damage were the #1 issues.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: cadillactim on October 28, 2012, 08:38:35 PM
Dave

Why was 85 the worst? I thought they had improved them in 85. I rebuilt a 83 one time, and even though the engine ran fine afterwards, I traded it shortly thereafter once I saw firsthand how the engine was designed. Before that I had a 82 that was running fine, then just locked up solid on the interstate. Couldn't turn the crank in either direction. But what were the design changes from 82-85?

My big concern would be the age of the sleeve O-rings at this point. Just being 27 years old would worry me.

Tim
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: 76eldo on October 28, 2012, 08:47:42 PM
79 had an Olds 350. 1980 and 81 had a Cadillac 368, same engine family and dimensions as the 472, 500, and 425.  In 1981 they tried a version of variable displacement and called it the V-864.  Solenoids controlled the variable displacement and were generally disconnected due to the problems encountered and then then you had a 368 inch motor with no computerized wizzardry.

In 82 and 83 the HT4100's were really bad.  Not that 84 and 85 were that much better, but at least they knew they had a clunker of an engine and started to do updates and modifications.  1985 was the best of the bunch of the 4100's.  Later in the 80's the punched them out to 4.5 and 4.9 but they were designed for FWD and mounted transversely.

1980 is the best of the bunch in my opinion, but a low mileage 4100 is possibly a safe bet, but always keep in the back of your mind that you can have sudden catastrophic failure and will have to dump 4K to 5K in the car to keep it running with a new or rebuilt engine.

Keep that in mind when you buy one.  There are some engine swap possibilities but they are difficult and require some engineering and parts from earlier models.

Brian
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: waterzap on October 28, 2012, 09:02:04 PM
Pm me your email. Will send you some articles on the HT4100. They made a lot of changes in 85. The pre 85 and post 85 blocks are very different. Check the oil, check the coolant. Intake manifold failure corresponds with milkshake oil. Drive the car and see how it feels. These aren't fast cars, but they aren't dead slow either. If it can barely climb a hill, the engine might have problems. Do you see any oil leaks?

Like anything, these engines can be fixed. A few thousand probably at most. A friend of mine had a VW Passat, and I think when his engine died it was going to be between $6k and $8k to fix. This won't be that much.

Where are you located? Just like the N* motors, you need someone that knows these engines if you ever want it rebuilt.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: waterzap on October 28, 2012, 09:08:31 PM
As a side note. Have had my 87 Deville with the HT4100 for a few months now. So far so good. Actually put around 300 miles on the car the last week. Not planning to drive the car that much, but taking a bit of a trip this weekend. Changed the coolant, oil, hoses, belt and a few other things, and so far the car hasn't missed a beat. Probably the nicest riding car I own. If I had the space and money and got offered a nice 85 Eldorado, would not hesitate.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: TJ Hopland on October 29, 2012, 12:54:11 AM
My questions would be:

What condition is the overall car in?

What do you plan to do with the car?

What sort of money are they asking?

Im looking at a 4100 car. I have owned them before.  Im not afraid of them.  Im getting it cheap enough that I dont care how long it runs.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Dave Shepherd on October 29, 2012, 09:52:48 AM
I was stuck trying to keep the dealers and shops happy keeping these engine/cars going, no HT 4100 came up to accepted standards back then, Cadillac tried their best to make them " tolerable". I am not even bringing into play unreliable sensors, gaskets, multiple oil leaks and low power complaints. So now everyone is so wary of the issues with that generation that a decent running one comes to the top of the heap like it was representive of all of them, not! On the other hand any of these cars still running today more than likely have have had major repairs already done or new engines sometime in the past.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Scot Minesinger on October 29, 2012, 10:10:40 AM
Aside from reliability problems the 4.1 is underpowered.  The way people drive today, even with my 472 you have to get into it a little to keep up with modern traffic at stop lights sometimes.  I would say that even with a perfect 4.1 you will not enjoy the driving experience if power is something you appreciate at all in a car.  If you buy the car and enjoy a little bit of pep, I would save for the installation of a 1979 drive train.

My Grandmother owned a 1982 Sedan DeVille with a 4.1 and she did not suffer any reliability issues during the first year they made them.  I drove the car on a 100 mile trip in 1983 at age 22.  It seemed that the throttle was set up so that at about one third depression of the accelerator you were at full throttle, giving the impression of more power than there really is at takeoff from a dead stop.  There is no good power on the open road.  She offered the car to me in 1990 as a gift and I passed due to the 4.1 under power issue.  My Dad eagerly accepted as the second alternate on the gift.  When my Dad picked up the car, he said "I wonder what engine this has?" with excitement.  Not surprisingly, within six months he sold the car because it was not fun at all to drive.

There are a lot of people who enjoy the 4.1, but I'm just not one of them.  For people who do not expect power from the standard of the world car manufacturer, then it could be just fine.  The 1985 Eldorado is a beautiful looking car from a non-mechanical perspective to me.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on October 29, 2012, 10:11:41 AM
 There were many improvements made by 1985. Once they had the sore spots identified, the updates began. Generally the '85 are OK, but they do suffer the same maladies of any aluminum engine if it hasn'r been properly cared for. You've heard mention of other Cadillac engines and the timing mchains, the nylon coming off and plugging the oil pick up. Same issue with these.

You want the coolant to be clean, the oil to be clean. And see of you can obtain the maintenance records. Proper maintenance is very important, even if the car has low miles.

Many of these cars have replacement engines too. GM replaced them with Goodwrench motors well into the 90's. These engines have the updates already incorporated into them, and they are good engines. They are a couple of quick giveaways to identify one, the easies is the cast aluminum rocker covers. The real identifier is the additional ribbing on the block.

These are beautiful cars both to look at and drive. And they can return some pretty good fuel economy numbers. They are not fast by any means, but can cruise pretty effortlessly at 70-75 MPH once you get there.

Mike
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on October 29, 2012, 10:19:42 AM

Oh, BTW, I p;urchased a used Goodwrench engine for my '85 Eldorado. I removed the pan, rocker covers and front cover to inspect the internals. I elected to replace the crank due to some scratching. The timing gear on this one is all metal. So I think It's safe to say the Goodwrench engines have steel gears.

At the time, the HT4100 was considered to have a pretty competitive specific output. The power seems very low by today's standards, though. Also, originally this engine was designed to go into the lighter FWD cars that debuted a year late in 1985. These cars perform much better. This engine in the full sized C/D cars really taxes them. The lighter E/K cars also have slightly better performance than the full sized cars.

Mike
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on October 29, 2012, 05:45:53 PM
Agreed with the posters who feel the 4100 had improved in reliability through the successive years. I once had an out-of-towner stop in with a '84 Brougham he had purchased new. The car had just shy of 400,000 miles. When I asked him what number engine he was on, he replied with a laugh that everyone asks him the same thing. Amazing isn't it?

The sad fact remains, and as I've said it before many times, this is hardly a robust engine. The problems that plague aren't just limited to an area or two, but many. Compounding the problem is that this is not an engine that likes to be tampered with as it ages. That means that if you go to do a head gasket job on your 30 yo 4100, chances are you'll find the steel bolts have electrolically "welded" themselves to the aluminum casting resulting in chunks of your engine block breaking off when you try removing them. Such occurred in my case resulting in a $2.200 Jasper reman engine plus another $800 in labor. External fasteners were no easier turning the simplest and most routine of tasks into a series of nightmares.

Personally I never had a problem with the lack of performance the 4100 is so noted. In fact they've always seemed quicker than the 307 Olds V-8 to me.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: waterzap on October 29, 2012, 07:16:48 PM
400,000 miles? Thats amazing. Just amazing.

All very good points about the HT4100, but it all really comes down to how much you spend on these cars. I think the HT4100 engine problems are built into the price of the cars by now.
If you can get one for $2,500, and spend another $3,000 for a new engine, you have a great looking, great driving car for $5,500. New shocks and a few other things, $6,000

Not much you can get out there for $6,000
A few months ago I rented a Hyundai Elantra for a cross country trip. I wasn’t impressed at all. I think they cost around $21k -$25k new for the one with AC and auto transmission.

The car was loud and the ride wasn’t as very nice. The $6,000 Eldorado with the new engine will probably ride better, be just as reliable, and look better. Bit worse MPG, but not that bad. You can buy a lot of gas for $14k.
Just my opinion.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: xcaret on November 20, 2012, 10:23:48 PM
Being an ex auto wrecker and driving an 1982,1985 and 1983 Eldo in the past ,Plus parting a few out , the thing I noticed besides not a lot of power was when the eng started going bad you could often hear a dull thud,thud sound coming from the engine at an idle. Being that I was only selling them used for $600.00 I never thought of repairing one ,just sold them to the core eng buyer. My 83 and 85 started doing the same thing. As for the rest of the car I have no complaints   
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 21, 2012, 09:05:03 AM
Quote from: austingta on October 28, 2012, 07:08:12 PM
IMHO, the ONLY years to buy that body style are 1979 and 1980. And then, not the diesel. The HT4100 is better than the V8-6-4, but only barely.

I would like to hear other opinions.

Sorry to differ but the V-8-6-4 is far superior plant than the 4100. There's really no comparison.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Tim Pawl CLC#4383 on November 21, 2012, 09:13:02 AM
1985 Eldorados after VIN FE623772 and 1985 Sevilles after VIN FE812094 had improved intake manifold gaskets and block casting changes.   Anything before that and you are at risk. We had a 1985 Eldorado Biarritz convertible with VIN after those shown and put 146,000 miles on it without issue, but changed oil every 2500 miles and coolant change with pellets every two years.
It is still around, saw it on the road this summer,  we sold it in 2003 , often wonder how many miles are on it now.   Tim Pawl CLC#4383
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Dave Shepherd on November 21, 2012, 10:40:34 AM
Quote from: ericdev on November 21, 2012, 09:05:03 AM
Sorry to differ but the V-8-6-4 is far superior plant than the 4100. There's really no comparison.
Agreed, basically the engine was an 80 368 all steel engine, the computer and rocker solenoid devices were the issue as the transition to 8-6-4 was very slow and caused customer complaints. Mileage was not as good as the HT series, but no engine issues at all.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 21, 2012, 11:00:04 AM
The transition between active cyliders was far less perceptible than an automatic transmission shifting between gears. Biggest annoyance I always thought was 6-cyl mode which was very rough. 8 was smoothest and 4 was okay. One of the "green lights" for variable cylinder operation was the transmission needed to be in 3rd gear so we'd just pull the plug from the transmission so they'd always remain in 8 cyl mode.

The primary issues the V-8-6-4 had nothing to do with its mechanical integrity which was excellent but with early electronics and/or the primitive connectors that were used. These issues had been addressed and sorted many years ago when '81s were active in the field. Unfortunately to this day, many still equivocate unreliability of 4100s and diesels with that of the V-8-6-4. Even diesels (1981-up or Goodwrench replacements) can get 100,000s miles of reliable service- properly tended.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: xcaret on November 22, 2012, 12:36:21 PM
The 80 v-8 368 eng was a problem for my mechanics here in Canada .We had a custom come in with some weird stuff going on and we failed to make sense of how to cure the problem so I phoned the local Cadillac dealer who told us there was no way to scan or diagnos the problems on that car , and they just replaced everything when a customer came in. After that I stayed away from them
Also does anyone remember the guy who bought one new ( I think it was the 4-6-8 ) and the dealer wouldn't honor the warranty so he hoisted it with a crane 80 feet or so in the air above a cement block and called the newspapers and told them since GM wouldn'thonor the warranty he was going to drop it ,and he did. That was in L.A. as I recall.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 22, 2012, 01:12:56 PM
I tend to take stories (such as the LA example) with a grain of salt as there's usually more to the tale. I once read of a similar one involving a (new at the time) early '70s Lincoln Mark in which an unhappy owner set ablaze in front of Ford's Dearborn plant after numerous failed attempts by the dealer to remedy its ills. Seems like an awfully expensive way of making a point: Insurance typically does not cover willful damage by owner.

As to the 1980 example- are we talking about the FI 368 (Eldo & Seville) or 368 carburetor (DeVille/Brougham)?
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: wrefakis on November 23, 2012, 08:07:17 AM
Guys I was a dealer all those years,and owned a 1984 coupe bought new as a road car,these engines were SO BAD,that you had to sell them AS-IS at dealer auctions even if they were still under factory warranty,again AS-IS for all engine knocks.

JUNK,in 72,000 miles on my 84 coupe,I did more major repairs,than in the last 550,000 town car miles.

Yes I love 59 and 65-70 Cadis,but as a dealer and owner that had 100's of these cars they were sharp looking cars with an engine that was JUNK from day 1 !!!
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 23, 2012, 09:42:12 AM
Back in the day the infamous 4100 helped bolster the value of the '80 model because if you wanted the newer style with a good reliable driveline, 1980 (and to a lesser extent, 1981) was your only option. I have a #2 '80 Coupe deVille with 22,000 miles and absolutely love it. 1977-1980 DeVille/Fleetwood were the best Cadillacs ever built from a standpoint of simplicity, comfort, usability and functionality- in my humble opinion.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: 76eldo on November 23, 2012, 09:50:57 AM
1980 was a good year for sure.

I went crazy when I found this one and paid a lot to get it.

I also have other Eldo's and a Seville with the 4100.  If taken care of they can last, with some luck.

Brian
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: 66 Eldo on November 23, 2012, 05:03:46 PM
Quote from: xcaret on November 20, 2012, 10:23:48 PM
Being an ex auto wrecker and driving an 1982,1985 and 1983 Eldo in the past ,Plus parting a few out , the thing I noticed besides not a lot of power was when the eng started going bad you could often hear a dull thud,thud sound coming from the engine at an idle. Being that I was only selling them used for $600.00 I never thought of repairing one ,just sold them to the core eng buyer. My 83 and 85 started doing the same thing. As for the rest of the car I have no complaints   

Based on my experience,  these engines had problems through the 4.9 versions. I had a 92 Sedan DeVille 4.9 liter with about 70k miles when I bought it. It had that dull thud or knocking not at idle but at first start-up for a few seconds until the oil pressure got up. You could also make it knock under a light power brake anytime.  Engine main bearings was the problem and was confirmed by an independent Cadillac repair shop operated by an ex-Cadillac tech.  He said that the 4.1, 4.5 and 4.9 engines all had a technical service bulletin (TSB) addressing undersize main bearings installed from the factory. The fix was to install the proper size  bearings. He had a Cadillac issued tool to do this with the engine in the car by "fishing in" the upper bearings. When he told me the price for the job, I didn't even want to do the job myself. It was reasonable,  under $800, which also included a new updated oil pan (another TSB) which was less prone to leakage. This was in 2002. He also mentioned that if you do this bearing update, install the pellets for the cooling system and don't overheat these engines, they can last a very long time.

As a side note, my brother-in-law was the general manager for a Cadillac dealership in the 80s and 90s. He said he had a lot of trouble selling used Cadillac with the 4.1 liter engines and had an arrangement with the factory rep to warranty a Goodwrench engine for all his used Cadillacs that were out of warranty even if they showed no signs of problems. There was no way he could sell one without a fresh motor because the public was well aware of the 4.1's problems. This was not a factory approved deal but since the dealership was high volume status, they got taken care of.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 23, 2012, 05:52:56 PM
The 4.9 bearings would get noisy but they were surprisingly inexpensive to replace. Last time I had one done, the local ex-Cadillac tech charged me $400 for a 4.9 main bearing job. 4100s were a completely different motor to work on. 
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Dave Shepherd on November 23, 2012, 07:48:31 PM
The mains failed from the long crank snout and the resulting overtightening of the belts pulling the nose of the crank up wearing the front upper main.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on November 24, 2012, 10:33:34 AM

Main bearing knock was an issue with the 4.1, 4.5, and the 4.9. But it was an easy fix, and no special tools were required. This knock generally occured when the engine was at operating temperature and at idle in gear. Noise at startup would likely bec caused by something else, like oil drainback after shut off. I have performed this job many, many times. part of the procedure was to check clearances before the new inserts were installed. In every case the clearances were within spec. Then you rolled in #1 and #5 inserts, torqued the mains then rolled the engine over by hand to make sure they were not too tight. This fixed the problem in every case.

Also, the 4.9 is of the same engine family as the 4.1 and 4.5. It is not a differant animal.

I have spent some time thinking about this problem. I don't know if my theory is correct, but it makes sense to me. The block is aluminum, the bearing caps cast irion. Aluminum has a very differant expansion rate than cast iron, and hence expands to the point where the clearances can increase where the crank can float causing the knock when the cylinder closest to the bearing fires. Also, this was not generally regarded as a detriment to the durability of the engine. Bearings that I removed showed no excessive wear.

Mike
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 24, 2012, 11:03:24 AM
On a couple of 4100s I've owned, the thump-thump-thump would be heard only at idle with the engine fully warmed up. Shifting into gear would make it disappear. On others it was just the opposite. One good thing about the 4100 is that they never had the piston slap the 4.9 had when cold. I passed on a ton of 91-93s before I realized the racket they made when cold was normal.

Although 4100/4.5/4.9 and even Northstar are genetically similar, I believe accessibility made the 4.9/4.5 bearings easier to replace. Not sure about 85-87 4100 (FWD). RWD was supposedly much more difficult. One thing I know for sure: I'd never be able to get RWD 4100 bearing job done for $400. Probably not a Northstar either but I've never had to have bottom end issues with N* to date.
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on November 26, 2012, 10:18:59 AM

Cold piston slap was an issue with the '91 4.9's. But is was never a concern for reliability or durability. I replaced many piston/sleeve assemblies under warranty and none showed any eveidence of even minor scuffing. I would not hesitate to buy one of these cars.

The Northstar is a completly differant engine from the 4.X engines. They share nothing with them at all. The architecture and even the basic configuration is differant. The only thing they share with the 4.X engines is the aluminum in the block.

Mike
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 26, 2012, 10:32:30 AM
Yeah, it was a while before I realized the cold piston slap was normal and was not cause for concern. As I'm sure you're aware, a lot of other GM engines did it as well: The 3100/3400 V-6, 4.8/5.3/6.0 liter V-8 in GM trucks and others. I'll tell you, the noise of a cold 4.9 sure scared many customers off back in the day.

Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on November 26, 2012, 11:10:20 AM

The Chevrolet 5.7 did that from day one as well. I have had several examples of this engine over the years, and they have all exhibited it to some degree. Both the LO5 in my '90 Brougham, and the LT1 in my '94 Fleetwood have it. Even the L-69 in my '76 Bel Air I had did it, and that engine was original and in excellent condition.

It was also common for the Cadillac 500 to do this. I have heard several examples of it. The 500 in my '75 Coupe deVille did it from the day I got it. I had that car for 12 years and it never got any worse.

Granted, it is a bit unnerving to have such a noise in your new Cadillac. But there is no cause for alarm. The noise often goes away after 20-30 seconds after cold start-up.

Mike
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: TJ Hopland on November 26, 2012, 11:11:12 AM
So why did piston slap become such a problem in the 90's?

I was going to comment on the comparison between the Northstar and 4.x's.   They are V8's and say Cadillac on them but that is about all that is the same.  If the 4.x had an iron block it would have pretty much been the same as any other pushrod V engine.    The Northstar I dont think had any one feature that was that new or innovative but it was the first engine where someone had put a bunch of new and innovative all together on the same engine.  If I remember correctly its like a lot of engines now where there is a whole lower layer to the block that contains the main caps and most of the oil passages.   As far as I know that and a lot of other features that engine had is pretty much a standard design on most engines now. 
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on November 26, 2012, 11:53:06 AM

The 4.9 is really just the 4.5 with a longer stroke. To accomplish this, part of the piston skirt was removed to allow the piston to travel lower in the bore. Typically, that skirt prevents the piston from rocking back and forth in the bore. When the engine is cold, the clearances are such that some of this rocking can happen, leading to the nopist that we call piston slap.

The tolerances can be tightened up, but that leaves precious clearance when the engine waqrms, and can actually become too tight causing scuffing on the skirt. This was an issue with the 1990 3.1 V-6. I replaced many entire engines under warranty for severe piston scuffing. The 2.8 from which it was derived already was prone to scuffing, and the tighter clearances exasperated the problem. Further versions of this engine, the 3.4, 3.5 and 3.9 are even more prone.

As many of us know, the 500 is the same engine as the 472, just with a longer stroke. The only differance in the engine is the crankshaft and pistons. The pistons have an abbreviated skirt which can lead to cold piston slap as well.

Mike
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Eric DeVirgilis CLC# 8621 on November 26, 2012, 01:52:11 PM
Thank you for that detailed clarification Mike. Learned a few new things yet again.

*When referring to "customers being scared off" I should've explained this was in reference to selling 4.9s on my lot as used cars- not new. I kind of think the slap wasn't too pronounced on the 4.9 when they were new. Once I had gotten to understand the reason, I was in a better position to explain it to my customers and most were okay with it. But you can imagine how I'd cringe when a customer would insist on first lifting the hood before starting the car on a cold winter day! The engine sounded like it was falling apart for those first 30 seconds.  :o
Title: Re: 1985 Eldorado - HT4100 Engine Problems?
Post by: Guidematic on November 27, 2012, 09:13:24 AM

Yes, they could be quite noisy on a cold day.

When we diagnosed which cylinder was making the noise, we would have the customer leave the car overnight outside. We would go out in the morning and start the car. Shorting out individual cylinders with a test light would reveal the noisy ones. The noise woukld quit once you shorted out a noisy cylinder.

Sometimes there would be more than one, and the engine would be quite noisy. I remember one particular customer that had several piston/liner assemblies replaced while the car was in warranty, some cylinders being replaced more than once.

Mike